Non-ionic Fluorinated PAG Polymers for EUV Lithography
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Solution Overview
Problem
Current EUV lithography resists face limitations due to image blur caused by acid diffusion and reaction propagation, and existing PAGs are ionic in nature, leading to low incorporation, high polydispersity, and poor solubility, which hinder resolution and low line edge roughness.
Innovation Solution
Development of non-ionic fluorinated PAG polymers with aryl ketone protected sulfonate ester groups that generate fluorinated polysulfonic acids upon photochemical deprotection, improving acid diffusion control and solubility for enhanced lithographic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ionic PAGs with sulfonate anions and counter ions are used, then photo-acid generation capability is achieved, but incorporation is low and polydispersity is high
Solution Approach 1:
The patent removes the counter ion component from the PAG structure, converting ionic PAGs into non-ionic forms. This extraction of the counter ion eliminates the charge separation that causes low incorporation and high polydispersity, while retaining the core photo-acid generating functionality through the aryl sulfonate ester groups.
Solution Approach 2:
The patent creates a composite structure by combining multiple aryl sulfonate ester groups with a polymer backbone in a non-ionic configuration. This composite approach allows for higher incorporation levels and reduced polydispersity while maintaining effective photo-acid generation through the cooperative action of multiple sulfonate ester groups.
2Reliability
If ionic PAGs are used, then photo-acid generation is enabled, but solubility in casting solvents is poor
Solution Approach 1:
By removing the ionic counter ion component, the patent eliminates the charge that causes poor solubility in organic casting solvents. The resulting non-ionic PAG polymer structure has improved compatibility with organic solvents while retaining photo-acid generation capability through the aryl sulfonate ester photolabile groups.
Solution Approach 2:
The patent changes the fundamental charge parameter of the PAG from ionic to non-ionic. This parameter change fundamentally alters the solubility characteristics, enabling good solubility in organic casting solvents while maintaining photo-acid generation through the photolytic cleavage of the aryl sulfonate ester bonds.
3Adaptability or versatility
If conventional resists are used for EUV applications, then existing photoresist formulations can be applied, but image blur from acid diffusion limits resolution
Solution Approach 1:
The patent converts the potential harm of acid diffusion into a benefit by using the generated fluorinated sulfonic acid to catalyze intramolecular reactions that lock in the pattern. The acid diffusion that would normally cause image blur is mitigated because the acid-catalyzed reactions occur rapidly and locally, converting the diffused acid into fixed chemical changes before significant blur can occur.
Solution Approach 2:
The patent changes the chemical nature of the generated acid to fluorinated sulfonic acid, which has different diffusion characteristics compared to conventional acids. Additionally, the use of photolabile aryl sulfonate ester groups enables more rapid acid generation, reducing the time available for diffusion and improving resolution while maintaining EUV resist formulation compatibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The fluorinated PAG polymers effectively reduce image blur and improve resolution and line edge roughness, enabling the formation of precise patterns with reduced defects in EUV lithography.
Implementation Method 1
aryl ketone protected sulfonate ester groups that undergo photochemically induced deprotection, generating a fluorinated polysulfonic acid
Data Source
AI summary
Non-ionic photo-acid generating (PAG) polymerizable monomers were prepared that contain a side chain sulfonate ester of an alpha-hydroxy aryl ketone. The aryl ketone group has a perfluorinated substituent alpha to the ketone carbonyl. The sulfur of the sulfonate ester is also directly linked to a fluorinated group. PAG polymers prepared from the PAG monomers release a strong sulfonic acid when exposed to high energy radiation such as deep UV or extreme UV light. The photo-generated sulfonic acid has a low diffusion rate in an exposed resist layer subjected to a post-exposure bake (PEB) at 100° C. to 150° C., resulting in formation of good line patterns after development.